1. Field of the Invention
The present invention relates to a mobile track working machine for rehabilitating a ballast bed supporting a track extending in a longitudinal direction, comprising a machine frame extending in the longitudinal direction and supported on the track by undercarriages for mobility in an operating direction. The machine frame is composed of a first frame part, leading in the operating direction, and a second frame part linked thereto. A longitudinal inclination meter is mounted on the first frame part for detecting an inclination of the track in the longitudinal direction. Working units are mounted on the second frame part, the working units being adjustable with respect to a vertical direction. A laser reference system is arranged on the machine frame for controlling the vertical position of the working units, the laser reference system being formed by a laser transmitter for establishing a reference plane and laser receivers for detecting said reference plane. An adjusting device is associated with the laser transmitter for relative adjustment of the position of the reference plane, and an odometer is mounted on the machine frame.
This invention also relates to a method for restoring a position of a track extending in a longitudinal direction, which position has been destroyed in the course of rehabilitating a ballast bed supporting the track.
2. Description of the Prior Art
A ballast cleaning machine formed by two frame parts which are articulatedly connected to one another is known from GB 2,268,021. A laser reference system serves for detecting the longitudinal inclination of the track in the region of the forward, first frame part in order to be able to control, in accordance with said measurement, the vertical position of working units located on the second frame part. To that end, a laser transmitter is provided which is permanently kept in a horizontal position. Arranged on the front undercarriage of the first frame part is a laser receiver which serves for detecting the longitudinal inclination of the first frame part with reference to the horizontal laser reference plane. The longitudinal inclination value computed via an algorithm is conveyed in a time-delayed manner to a further laser receiver located on a clearing chain on the second frame part in order to thereby be able to control the vertical position of the clearing chain.
Additionally known from GB 2,268,529 is a ballast cleaning machine in which respective longitudinal and transverse inclination meters are fastened to a first as well as to a second frame part. The longitudinal inclination of the track measured in the region of the first frame part is stored as a desired value and passed on in a time-delayed manner for controlling the vertical position of a clearing chain. To that end, the actual, existing inclination detected by the longitudinal inclination meter of the second frame part must be taken into account. For the purpose of controlling the vertical position, a cable potentiometer is provided which is arranged between the second frame part and the clearing chain. Since reproducing the position of the track is accomplished via the second frame part, inaccuracies caused by twisting or deflection of the frame cannot be precluded.